SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '894762514874fafb9d1e004ccff86790a8e7142902868e692cbd1cbc20adbf38' 
  AND token = 'lkMumAlsWxRCmozwTMTZ/AXw2Fi9TBcJN2jfolYPgnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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