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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '892b55f73001ef9680e64240e3a99df55a7909d132b4a504327d374f2273113f' 
  AND token = 'nVJRuhFFkeGSKEdwfVZ037o30/ORo8A0xB5xOeQSEMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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