SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f6ce6c10381167edde847e0918032bdebffda6fee43cee888f640a5b3c0a6b5' 
  AND token = 'j5RT8Ct0HpiZktCpbTOciys8EQzAHuZjzMzlyupvmcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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