SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c9c7425c2542e8d80aaf02bd33fc1548df06642cd059027196992524930a1d9' 
  AND token = 'OnHmBOkqn4aV2b3gw+JTBvd8aXD+ULTfejrePGlpRXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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