SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '875b0afc326b04205d5271464c1eba16a20b5587912d484526444a3333da562b' 
  AND token = 'ZRiRPCcpbDxFqE+g6yBho9Joj/G5lRz9gvmXrW9ImTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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