SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b360817a3c9997094cb763dacf03c8911d836c0685b58bf7bc388bed8f1bd7c' 
  AND token = 'xJ+unkQCf3TwAYZLdGpqRVe7dIXeH49C0di6tdIhHMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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