SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6981fa03cb064e72145f91757b9e86577459b9ea2263bab8229747b61267124' 
  AND token = '8tRRcpKBvKaepa2dqWJK4d/nMTV+BoMCSyG4EbAWLzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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