SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8356fbc48046c5d65de801641ba8448312e3c642607d6cf0c1565084e3e8ab83' 
  AND token = 'IgnNTt1PgcTFtpvaRrZv6Wzc+Gy93CP+sVpmb38ydRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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