SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39a697b2589d7b031ca43099ed046d2069f6689014a95d5b43d718a4d6528ff1' 
  AND token = 'DqKD0G1q24+1ZQEamsWm1xvTyiRawOED/zBgy9DJVtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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