SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2958ec66b19ce4b696dbfc37a14300177ff501cfce4b9e02042814c03a4fe843' 
  AND token = 'vLvJFDer27CjpNqRSz7mzIhFpXUHon+H5rNjvBixRHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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