SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7a43d232f2c91996472ed15fc11ddd8341486dda053645789c7ca81caf8818b' 
  AND token = '3QD0NqRqdId8qVlIZ8OPmYm8+owgl6C5eBxFe3D+ac0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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