SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12342cf360129b973193ca9110fc5fa92d9588f1dabc668b754ea68748fc6fac' 
  AND token = 'CjZ41U+jVMerD0tnh2BlOgabfIRZCxOIdVAdhwGXvdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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