SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd03ce1d4c44842400e94eae4dbdbd012dcd36602181c1ebd684483812fb273d0' 
  AND token = 'gy/hchdIKSogZunBvBpGbM58bnnusHqdIu7d5qeM8D0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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