SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21d1fc560e6e7d461b5b17cd653ea012a0e44d30298f387fed3bfcc2ca5bf8ab' 
  AND token = 'jvgYWtIuRDCddgcusuTe4VOIqpdRPgpjeCA2tIvv17k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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