SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f96ebe9a3ac3f6ff1083f7d8e606b84d356ca648e06a6b9bba6482737e62b534' 
  AND token = 'fpjqLCrQrdiDj4x7acxcosT2S+HUHY+/cWAzp3HCNV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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