SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef9e2ac14f8c48d1c5f15e886a02460960c8b0ac3478e829425659d898a18616' 
  AND token = 'RCq6lXjYsjnffBTzto2RGzAD7Q26Ee6TTJQPGZDWS8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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