SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3024378fc10f1b973c577d2c9b1026618466685559331265594cd10ec5eef59' 
  AND token = 'WqfPFkjUN4u0gbmbA3kh3rSDds7EQEEnNPwLZd3vD/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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