SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a08d78cd0d5a9dfe35e5970f0ec5187086d6319b4d7903d005d6d1e2e1b2df8' 
  AND token = 'GUawdAlhG+pv8FMD0VhZBQup9joYpjN6oApClRq4HqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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