SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3ab1883dd084b26cd3e40ca0a01c37a917cb4b146825e516e85c0bad86bca0e' 
  AND token = '9np8I77X/2ydniLbowjWHkTl9ZW520u72mT1y0lt390=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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