SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a896a32424d5384e141d402bf968f1539e92c3bf22969e7bd434e5f952d2fb89' 
  AND token = 'UM//4bTX4r+hTg0gECY+Y6AqSl1zjaeh8NBHd6RABpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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