SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c981985ab6ccb2934e4b21c07cf6961ffa8b0c5578bbaa6389895823a4d8043' 
  AND token = 'KTdCmWlCEajVTCVV8zZh+MDJ0AOuHSAVWzjvJ9pMjNM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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