SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e5a193c70356beb1035107910f9785a775f9dc79a1ff37c0fc2d4c35452ed22' 
  AND token = 'Rfw1S8cX/XXCB/ZMwZBhYjQK3sjvtNw4whtdmLd+kA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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