SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '502fccb2972a12338e86147a201f9f5c2f25554db4057212e0a941f836dabfc0' 
  AND token = '06qbLZGjBRBU7FNSgCvKBmhAWLo2oImsgQXBcxTgDpE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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