SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87f398d89806081ffe588c2a3bbf17933de8f3258e248ed82093f323369620a5' 
  AND token = 'qPcA93ZqQg0XMCVHAIHc2b2+fyhzkeh1PAYVoz1YMho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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