SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53d5b28952f58bfa2a7f777d54ea2963977dce376389a3f553c966718f9aee8b' 
  AND token = '6l8JaVDAwWTMoGfkiLFcv+kpFGMF5J49/F0nzxkJUyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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