SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39b960fe1aae61119b485c002c9937c19f6b673e41f82a7f420fef5de0298987' 
  AND token = 'EFRwFQDMb22zxdYICsQujG+ajmgBjismlDYnyjXGVZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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