SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '946d46116a43c248e4be4fa6018844cca688d4f51a9a7e456aa232be6d48bca4' 
  AND token = '0ndx2IXP82iLUSRD6SUDuBHZ8mbkR4wyynIzf3aaqjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00076

JSON explain

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