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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f56e93bfd69c6bffb9208f96782221fa12e5018ca9c00cfee3f62b7a1e1eeb1d' 
  AND token = 'i2LjXf2bH//Cg8ZESlJZ19dWqjxsIuUQMmX3ffBxrdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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