SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43001b42f1b065d4a63fca8505d0f29cc50185f76667a343f25c2c04dda4f853' 
  AND token = '8/pVZo0CxPm7HUp17+JlCKrkhJPYIJW+OUGO1lV6vCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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