SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a75c7ba561ebfce3bc1fba45343810a7c3b68b369710dc8bff41b99824df208d' 
  AND token = 'Xl7C3VlF+V/QKLTU70kZ6NhwZGl5JDXsYk9550DZ6wc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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