SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da0847a8770f75104b7bdb0deadca3c13e51d60c199f87efee6b7e8711ede4d8' 
  AND token = 'JlT0LbrYtdBPTBaCCtJla1hbREHr/LUN4mLPqUnWe50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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