SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91e3f3c01d00c22a1b6a16fd42a5c20633f9344adf2b5d537f827fb87e46925c' 
  AND token = 'O3DRVkKG+E5ds3XKGmLWAupYrQB3gVZaHjLbCn78fK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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