SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c733ffbbd6b034eddab672168e378d16478c4db51911dc53c7512c28a51f78e' 
  AND token = '8jHLn4MCQg0joOyChueP2gQJJYtjWwqO1v+sGcLdqfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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