SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6529a38f2248bfb18fafb2aca015895e82e83c2b1ee3e77d295d551171694386' 
  AND token = 'OcIFoNaCqnvnhInvWVBknLY5gMt3ceFVqG2qGER3oRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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