SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f635148d4b043ed441e60c0159a423843ae05365cd8ba12932ebecb6a0648854' 
  AND token = 'BYt1dvRmtpWIhmWwhWTcRIOt+KqPMHxy9IgExOsJPiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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