SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca48eba7a201e3909debbbacdf6c5259f05a1229fea4b55ecece16a414d50ded' 
  AND token = '71QzHUAmxE7U2HoffwHkH9trrPSmhyEYbOMBbDocpc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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