SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '455d24fa3152b026ac935e30a4507da995f814c0d9d2768912f635c17a4696cf' 
  AND token = 'RmQGAagcQkE2hNdw3XNkfpEtoMgHfpNTFGh8pcRpeUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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