SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19c138733a1168465e8c77376e42b3be9e34615b6fcc5fb632d91e95f676537b' 
  AND token = '2RagSkJOBuCz1W32TG9KjXX4s+6+/8gGiRDRHXhZOUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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