SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8274a6e7344c5f9251f56985735d91bf9dbdc1c94170eb59ea22ea9ad4a91968' 
  AND token = 'RcLkSCQHVfPMOvV68nUn9Xo+KiqZjyzEbIWu3sY5Pxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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