SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34752c12fd89915f8c59789ee1f7d4c5280d1d888726cb3ffff783effcfafcb3' 
  AND token = 'UXkE18PofzQzxXTzOGLr7x9xbP2JQq3FBmsBwlHnYBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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