SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50976ed9e2c7ee1cff08706127f75560ec77b7ad9d1a2def977c9b0ead9e4179' 
  AND token = '5sOB0kNKpNiK9/yyy7wqFEE+T/OZ4wX458hkMg3XQ10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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