SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f7326844541c1ee6b35fef1155021184cd5eb2ce37d39bd80a48624be2f92dc' 
  AND token = 'XUomtQbVfJZPmeX1r+ISNcRGPSAKIx9HScGhg/QwbBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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