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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6c576b5198069b48bd77582fa63b8200d143d5688b13cfba81c94396d4366aa5' 
  AND token = '9+nHAxBIiDDAHSk2ogyEyHmQ8Z2wSkxaOzNKxN07Ij0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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