SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6e96fcda2fa364283791720f63d6ed5a0fbc072649bafa816659111c52c7dc0' 
  AND token = 't5pRniw0xW+/0iR6YjMql50f+34i3XeoEfVKg/MtCz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00050

JSON explain

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