SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77b39f12d17be944723271e1102e002aa7b5d847d2380c561292e6f9a738e833' 
  AND token = 'YluFKkaFi6/BmccPGkjuBrzNsnIFLKmVFvPD2JwYPdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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