SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e70e70509800f0b7f758d876f4646e12e80f70b833ebadaf014edac7450eb308' 
  AND token = 'F8Qi97c6oWvVBoOJ5eZtSA6h45yh6yQbljpyDTp2KXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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