SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cd80af1d0d750f09731b00853452d1b9f710eb2483472f8e80d6d7207e9bacb' 
  AND token = 'q255yHSHE/PiqDtgR5GIzlLkXgt9LG1aU05CuoV0+bA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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