SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ab87e9a5174062de2a227e594558267576c4b48cb71a57889fb1bfd43030ee6' 
  AND token = 'O+4MrE8H+rlB6OYZ8pr4JRFltizK3TDL8VF+GgqFUGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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