SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91d1f1677b778051f15f305202c682445325e947198607b58e9314d373ab229e' 
  AND token = 'kRBArOnE0Rg+EulghDTTmaNjhKQi3+zpbEzGpaIvMZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}