SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca035996a4627340c79a79f3a953e6bb6e10fd617ca1b9c02afee253860cfeba' 
  AND token = '6TdUQ4s5aJswUXwmsE4Q0Wa3ejqUB/Z3eTEcwTX4RKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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