SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bcf034bdf1010b085fe76c71bb8b34b597628193143917d5693099c10d7e854' 
  AND token = '125KIn+oDwlwLvnzM1PtuUwYjMzFEfmAtxMmalveAyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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