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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a6eadc8d00985de1d366128d634fec83b85af8fa3c1eff86ae4761d37d8fd48b' 
  AND token = 'k+N7nHCaYmhebcwz5txGF7FFy9II7FLrU/1ocOhAt+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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