SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a33a738a468b8dfba0f7a2188aba5782601385aeff5030f8a513a9e503b0de16' 
  AND token = 'UyTGUuHRk5/ezQxbKIjYKCTqg59O/hl6zp9EfDtqHXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}