SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cd24d876d82f2109a2018392b208dfd61a2331f6d43312f7816cd646d392109' 
  AND token = 'UOt8SjDDTf+QC5w+OKZluDJQtrANdV0dwk0RRVf4898=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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