SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4426da24dfc092bab17144252e42eda684a3c3e90349e2b244bb5416296aabc2' 
  AND token = 'u8ky14vLYLWD9vofkNYFD8v0zPG2a8XUvJauqtBUro0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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