SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '956a7231b6b7ef4c510667aa71e4e2fc89cfdd3ab71b9868dcceec544f924a1b' 
  AND token = 'U+Smi89FGfe4Q1sxiZdTiXl5HvnmA2EfsGGAQcYkOUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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