SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f50aec37a6bf21982b3050e4f3755f43adb21c5d1256c2348d163713e0015eb1' 
  AND token = 'pBxbXVGQ/G/5s2ith83OPdipefkq2zjYNcIJFlC9zkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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