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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b2ea917460435a7496899e604bb72f7b17c84b3cbfa7d5ee59b2239b17aeffe1' 
  AND token = 'Nm0hrqUE/Rl3rYny9zzu1Cissm8zSifxdbmfmv+Vqds=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}