SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14a6a68e43d65362c51c8b5f093480608df07012d0a8fe4af3cbe075795708dc' 
  AND token = 'EtRauY7CF5/uBAuQpxMVE3EPKoprKguvVPj0FtlWGx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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