SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a57a1ab81a2574a3fce166718859db435c3f1106541b98ef21c2d811315a4ab0' 
  AND token = 'RP3R71iYTF2FSekNfsCSMZc8MyviI1RV1usIUAhTreU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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