SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8b3777ccf8b1d0079313e551b68001c560f8fe6b55ad09e70b15afa92cf0671' 
  AND token = '8PLykjkwD9BmPdRyg0wX00Yq8xt74/nS5dWyufyHWfc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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