SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd76759efd3378659547ffd1bac2a1cf6188fb9c5017a8f0517a17df6d403255c' 
  AND token = 'CjTMcUaWbCHCy2sv3mgXrstdt8UeYADvGeO7tZOL1m8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}