SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2a2f44ead8095ab8e4d92f6ccca2d3c85197189800d7e4221f0ed879eb4eaac' 
  AND token = 'p3VYi3x3iJnGoX8wDcE1hJg+pKYSzoQMyPiEB1ZPpOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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