SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e787839e35546f8a48188abebcd7b532791fc7d08649980f2179a61f013e029b' 
  AND token = 'xLTVb/9P0khliCWt+BVFb5EabmzJrYrby5+LhJgpep0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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