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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17c5f5bc81ff2bffe8d093a188f70a0c9744b41334f601e52d92a2d3e3b16c55' 
  AND token = '5ihcfdQcXWIyblVtLhznbbkkcqDcBNYARj0+ixST6eU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}