SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '564233a265dafe546494854e641115572cb936e715095bd2131bbb1013b265ac' 
  AND token = '9k49jtjIQM481HQ8eInY+AHAezwylIH3TT3jW8KMrvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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