SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f8848b4663f0dd9788fd488ee957226e15145996905508783f6b5c216ac5f5c' 
  AND token = 'qz7wZ3Fszh+gokfPZxzyFTbyqRN/H+djHYfC27ACpmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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