SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45e54911c1b11a5800334eda6cfebe14b35f6f9e245640322aea5e460083a482' 
  AND token = 'AJxLufeE5c4mygyjVdP7hM7AyFPJWkFCEYSTC4t5dyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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