SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2869977207048daf31bad865f64c6f04b45934fd603288238ac41521ac4ba999' 
  AND token = '71qzcKqzuVbsY51HfzxOSAwxTQMflMLN8b4RiCNX/rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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